Make number of levels available.

[[Imported from SVN: r1056]]

istl/paamg/amg.hh

@@ -136,6 +136,8 @@ namespace Dune
       template<class A1>
       void getCoarsestAggregateNumbers(std::vector<std::size_t,A1>& cont);
 
+      std::size_t levels();
+
     private:
       /** @brief Multigrid cycle on a level. */
       void mgc(typename Hierarchy<Smoother,A>::Iterator& smoother,
@@ -296,6 +298,11 @@ namespace Dune
                                         *coarseSmoother_, 1E-2, 10000, 0);
       }
     }
+    template<class M, class X, class S, class P, class A>
+    std::size_t AMG<M,X,S,P,A>::levels()
+    {
+      return matrices_->levels();
+    }
 
     /** \copydoc Preconditioner::apply */
     template<class M, class X, class S, class P, class A>